As a compressor to perform the compression stroke in the refrigeration cycle in a refrigerator, a compressor employing a non-contact bearing such as a magnetic bearing as a bearing for the output shaft of the motor driving the compressor, is used. The non-contact bearing supports a rotation shaft of e.g. an output shaft of a motor without contact. Thus, in comparison with a rolling-element bearing, which supports a rotation shaft in contact with the rotation shaft, a non-contact bearing does not cause mechanical friction loss with a rotation shaft and it is excellent in durability due to no friction. Thus, a compressor employing a non-contact bearing such as a magnetic bearing as the bearing for the output shaft of the motor is used when the motor is supposed to be used at a high rotational speed, for example.
Patent Document 1 discloses a turbine compressor employing a magnetic bearing where a turbine impeller is mounted on an end and a compressor impeller on the other end of a shaft and the shaft is supported by the magnetic bearing, which is an example of an expander-integrated compressor employing a non-contact bearing as described above.